Allied Telesis AT-GS950/48 - Manual (Page 347)

AT-GS950/48 Web Interface User Guide
347
General Guidelines
Here are the guidelines for MSTIs:
 The AT-GS950/48 switch can support up to 31 spanning tree instances,
including the CIST.
 A MSTI can contain any number of VLANs.
 A VLAN can belong to only one MSTI at a time.
 A switch port can belong to more than one spanning tree instance at a
time by being an untagged and tagged member of VLANs belonging to
different MSTI’s. This is possible because a port can be in different MSTP
states for different MSTI’s simultaneously. For example, a port can be in
the MSTP blocking state for one MSTI and the forwarding state for another
spanning tree instance. For further information, refer to “Ports in Multiple
MSTIs,” next.